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Title: Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy

Abstract

Characterization of dominant electron trap in as-grown SiC epilayers has been carried out using deep level transient spectroscopy. Two electron traps E1 and Z{sub 1} at E{sub c}-0.21 and E{sub c}-0.61 are observed, respectively; Z{sub 1} being the dominant level. Line shape fitting, capture cross section, and insensitivity with doping concentration have revealed interesting features of Z{sub 1} center. Spatial distribution discloses that the level is generated in the vicinity of epilayers/substrate interface and the rest of the overgrown layers is defect-free. Owing to the Si-rich growth conditions, the depth profile of Z{sub 1} relates it to carbon vacancy. The alpha particle irradiation transforms Z{sub 1} level into Z{sub 1}/Z{sub 2} center involving silicon and carbon vacancies. Isochronal annealing study further strengthens the proposed origin of the debated level.

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. Semiconductor Division, The Islamia University of Bahawalpur, 63100 Bahawalpur (Pakistan)
  2. (IFM), Linkoeping University, SE-58183 Linkoeping (Sweden)
  3. (Pakistan)
Publication Date:
OSTI Identifier:
20982798
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 101; Journal Issue: 7; Other Information: DOI: 10.1063/1.2715534; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALPHA PARTICLES; ANNEALING; CAPTURE; CARBON; CROSS SECTIONS; CRYSTAL GROWTH; DEEP LEVEL TRANSIENT SPECTROSCOPY; ELECTRONS; EPITAXY; IRRADIATION; LAYERS; SEMICONDUCTOR MATERIALS; SILICON; SILICON CARBIDES; SPATIAL DISTRIBUTION; SUBSTRATES; TRAPS; VACANCIES

Citation Formats

Asghar, M., Hussain, I., Noor, H. S., Iqbal, F., Wahab, Q., Bhatti, A. S., Department of Physics, Chemistry, and Biology, and Department of Physics, COMSATS Institute of Information Technology, H-8 Islamabad. Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy. United States: N. p., 2007. Web. doi:10.1063/1.2715534.
Asghar, M., Hussain, I., Noor, H. S., Iqbal, F., Wahab, Q., Bhatti, A. S., Department of Physics, Chemistry, and Biology, & Department of Physics, COMSATS Institute of Information Technology, H-8 Islamabad. Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy. United States. doi:10.1063/1.2715534.
Asghar, M., Hussain, I., Noor, H. S., Iqbal, F., Wahab, Q., Bhatti, A. S., Department of Physics, Chemistry, and Biology, and Department of Physics, COMSATS Institute of Information Technology, H-8 Islamabad. Sun . "Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy". United States. doi:10.1063/1.2715534.
@article{osti_20982798,
title = {Properties of dominant electron trap center in n-type SiC epilayers by means of deep level transient spectroscopy},
author = {Asghar, M. and Hussain, I. and Noor, H. S. and Iqbal, F. and Wahab, Q. and Bhatti, A. S. and Department of Physics, Chemistry, and Biology and Department of Physics, COMSATS Institute of Information Technology, H-8 Islamabad},
abstractNote = {Characterization of dominant electron trap in as-grown SiC epilayers has been carried out using deep level transient spectroscopy. Two electron traps E1 and Z{sub 1} at E{sub c}-0.21 and E{sub c}-0.61 are observed, respectively; Z{sub 1} being the dominant level. Line shape fitting, capture cross section, and insensitivity with doping concentration have revealed interesting features of Z{sub 1} center. Spatial distribution discloses that the level is generated in the vicinity of epilayers/substrate interface and the rest of the overgrown layers is defect-free. Owing to the Si-rich growth conditions, the depth profile of Z{sub 1} relates it to carbon vacancy. The alpha particle irradiation transforms Z{sub 1} level into Z{sub 1}/Z{sub 2} center involving silicon and carbon vacancies. Isochronal annealing study further strengthens the proposed origin of the debated level.},
doi = {10.1063/1.2715534},
journal = {Journal of Applied Physics},
number = 7,
volume = 101,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}
  • No abstract prepared.
  • The authors have investigated deep levels in as-grown and electron-irradiated p-type 4H-SiC epilayers by deep level transient spectroscopy. In as-grown epilayers, the D center and four deep levels are observed. In p-type 4H-SiC, reactive ion etching followed by thermal treatment (at 1150 degree sign C) induces the HK0 (E{sub V}+0.79 eV) and HK2 (E{sub V}+0.84 eV) centers. By the electron irradiation, two deep levels at 0.98 eV (EP1) and 1.44 eV (EP2) are observed in all the samples irradiated at 116-400 keV, while two additional deep levels (EP3 and EP4) are observed only in the samples irradiated at 400 keV.more » After annealing at 950 degree sign C, these centers are annealed out, and the HK4 (E{sub V}+1.44 eV) concentration is increased. By the electron irradiation at more than 160 keV followed by annealing at 950 degree sign C, three deep levels are always observed at 0.30 eV (UK1), 0.58 eV (UK2), and 1.44 eV (HK4). These centers may be defect complexes including carbon displacement-related defects. All the centers except for the D center are reduced to below the detection limit (1-3x10{sup 11} cm{sup -3}) by annealing at 1550 degree sign C for 30 min.« less
  • Higher-efficiency solar cells improve the likelihood that concentrator photovoltaic systems will become cost effective. A four-junction GaAs- and Ge-based solar cell incorporating a 1-eV bandgap material has an ideal AM0 efficiency of ~40% and could also be used in a terrestrial concentrator module. The dilute-N GaAsN alloy's bandgap can be reduced to near 1 eV when the nitrogen content is 2% - 3%. Indium can also be added to the alloy to improve lattice matching to GaAs and Ge. We have used deep-level transient spectroscopy (DLTS) to characterize traps in both p-type and n-type GaAsN. For each type of material,more » the dominant DLTS signal corresponds to an electron trap having an activation energy of about 0.35 eV for p-type GaAsN and about 0.45 eV for n-type GaAsN. In both types of materials, the trap concentrations, modified by ..lambda..-effect factors, increase with both increasing N content and increased doping.« less
  • Spectroscopic performance of Schottky barrier alpha particle detectors fabricated on 50 μm thick n-type 4H-SiC epitaxial layers containing Z{sub 1/2}, EH{sub 5}, and Ci1 deep levels were investigated. The device performance was evaluated on the basis of junction current/capacitance characterization and alpha pulse-height spectroscopy. Capacitance mode deep level transient spectroscopy revealed the presence of the above-mentioned deep levels along with two shallow level defects related to titanium impurities (Ti(h) and Ti(c)) and an unidentified deep electron trap located at 2.4 eV below the conduction band minimum, which is being reported for the first time. The concentration of the lifetime killer Z{sub 1/2}more » defects was found to be 1.7 × 10{sup 13} cm{sup −3}. The charge transport and collection efficiency results obtained from the alpha particle pulse-height spectroscopy were interpreted using a drift-diffusion charge transport model. Based on these investigations, the physics behind the correlation of the detector properties viz., energy resolution and charge collection efficiency, the junction properties like uniformity in barrier-height, leakage current, and effective doping concentration, and the presence of defects has been discussed in details. The studies also revealed that the dominating contribution to the charge collection efficiency was due to the diffusion of charge carriers generated in the neutral region of the detector. The 10 mm{sup 2} large area detectors demonstrated an impressive energy resolution of 1.8% for 5486 keV alpha particles at an optimized operating reverse bias of 130 V.« less
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